CN111975909B

CN111975909B - Multifunctional metalized wood material and preparation method and application thereof

Info

Publication number: CN111975909B
Application number: CN202010822953.1A
Authority: CN
Inventors: 杨宇; 楚状状; 杨卓鸿; 李维桐; 卢梁美; 彭粤海; 刘飞
Original assignee: South China Agricultural University
Current assignee: South China Agricultural University
Priority date: 2020-08-17
Filing date: 2020-08-17
Publication date: 2021-06-04
Anticipated expiration: 2040-08-17
Also published as: CN111975909A

Abstract

The invention belongs to the field of natural polymer modified materials, and particularly relates to a method for preparing a multifunctional metalized wood material by using wood. Firstly, performing alkali treatment and bleaching on wood to remove hemicellulose and lignin to obtain porous wood which is rich in cellulose and has excellent elasticity; then, the porous wood is subjected to simple oxidation reaction to prepare oxidized porous wood; then, carrying out glutaraldehyde crosslinking reaction on the oxidized porous wood and functional polymer polyethyleneimine to obtain polymer wood with chelated heavy metal ions; finally, the polymer wood is subjected to metal electroless deposition to prepare the metallized wood material with the advantages of porosity, stable metal layer and good compression performance. The metallized wood material prepared by the invention has excellent catalytic and cyclic catalytic effects, good conductive capability and outstanding antibacterial property, and has positive value for widening the application of natural biomass resource wood and improving the added value of the natural biomass resource wood when being used in the fields of catalysis, conductivity and antibiosis.

Description

Multifunctional metalized wood material and preparation method and application thereof

Technical Field

The invention belongs to the field of natural polymer modified materials, and particularly relates to a multifunctional metallized wood material with catalytic, conductive and antibacterial properties, and a preparation method and application thereof.

Background

Metallization materials with large surface areas have received much attention due to their potential applications in the fields of electrochemical energy conversion and storage, catalytic degradation, antimicrobial, etc. In particular, metal particles and wires of nanometer dimensions have proven to be promising candidates in the fields of catalytic degradation, antibacterial, electrical conduction, etc. However, these nano-scale metal particles and wires are easy to aggregate irreversibly, and are difficult to be reused, which seriously affects the applications in the fields of catalysis, conductivity, antibiosis, etc. To address these problems, one of the main strategies is to immobilize these nanometals on various substrates, such as silica microspheres, graphene sheets, metal organic frameworks, polymers, hydrogels, etc. The stability of these metallized materials will be greatly improved after being fixed on a substrate, and the various properties thereof will be remarkably improved. However, the synthesis of these metallized materials is often extremely cumbersome, greatly limiting their large-scale use.

Another strategy to get rid of the cumbersome manufacturing process and separation procedure is to deposit the metal particles/metal layers on different substrates by different methods, including Physical Vapor Deposition (PVD), galvanic deposition, chemical deposition (ELD), etc. The PVD method requires expensive equipment, complicated preparation environment and cumbersome process conditions, which limits its large-scale application. Electroplating deposition is a mature method for depositing metal and is widely applied to large-scale production in laboratories and enterprises, and although the technology can realize the deposition of the metal at lower cost, the substrate of the technology is required to be a conductive material, which limits the application of the substrate of a non-conductive high molecular material; in addition, the deposited metal is less adherent and therefore tends to crack and separate from the substrate during use. The ELD technology is an ideal choice for surface metallization of high polymer materials due to the advantages of mild and simple process conditions, low cost and the like. ELD technology is essentially an autocatalytic reduction reaction that allows the deposition of metal particles on a substrate pre-loaded with a catalyst, and more importantly, the substrate comprises almost all non-conductive flexible and rigid materials such as polydimethylsiloxane, polyethylene terephthalate, polyurethane, paper, carbon fiber, and the like. In addition, in order to solve the problem of weak adhesion between the metal layer and the substrate, researchers have introduced long-chain functional polymers into the ELD process and developed a polymer assisted metal deposition method (PAMD) which can significantly improve the adhesion of the metal layer and stably deposit the metal layer on the non-conductive substrate. Therefore, in order to respond to the national emphasis on the environment-friendly society and the sustainable resource development, further development of a green, environment-friendly and renewable non-conductive substrate is urgently needed.

Cellulose is the most abundant natural polymer material in nature, and has good development prospect in the fields of catalytic degradation, electric conduction, antibiosis and the like due to the advantages of good biodegradability, no toxicity, excellent chemical modification capability and the like. Wood, a carbon neutral biomass resource, contains about 45% cellulose. Due to the low environmental, health and safety risks, the wood can be used as a preferred raw material to obtain the traditional and advanced functional material through chemical modification. The traditional method is to remove lignin and hemicellulose from wood to obtain porous wood with excellent mechanical properties, and the porous wood is used as an attractive substrate material in the PAMD method. However, some polymerization methods, such as surface-initiated atom transfer radical polymerization (SI-ATRP), must be reacted for several hours in an inert atmosphere, and thus, it is difficult to expand them for use in synthesizing metallized wood. Therefore, it remains a significant challenge to prepare stable, efficient metallized wood using a simple, mild, and environmentally friendly process.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the preparation method of the multifunctional metallized wood material with catalytic, conductive and antibacterial properties by taking the wood as the raw material, further widens the application field of the wood and improves the added value of the wood.

In order to solve the technical problems, the invention is realized by the following technical scheme:

a preparation method of a multifunctional metallized wood material comprises the following steps:

(1) cutting wood (basswood, balsa wood, pine wood or birch) into blocks (no more than 10 cm)³) Soaking the wood in a boiling mixed aqueous solution of sodium hydroxide and sodium sulfite for reaction (4-12 h), taking out the wood after the reaction is finished, soaking the wood in a boiling sodium chlorite solution (with the mass fraction of 0.5-1%) for reaction, taking out the wood after the wood is whitened, fully rinsing the wood with water, and then (freezing) drying the wood to obtain the porous wood (rich in cellulose). Preferably, the concentration of sodium hydroxide in the mixed aqueous solution is 10-40 g/L, and the concentration of sodium sulfite is 30-50 g/L.

(2) Soaking the porous wood obtained in the step (1) in water with the pH value of 8-12, then adding a certain amount of sodium hypochlorite to enable the concentration of the sodium hypochlorite in the solution to reach 5-15mmol/L, reacting for 2-5h, then adding a certain amount of hydrochloric acid (preferably with the concentration of 0.1-0.5 mol/L) until the pH value of the solution is neutral (the pH value reaches 7), stopping the reaction, taking out the wood, soaking the wood with hydrochloric acid (preferably with the concentration of 0.1-0.5 mol/L), then washing the wood with water, and drying (freezing) to obtain the oxidized porous wood.

(3) And (3) adding the oxidized porous wood obtained in the step (2) into a methanol solution of polyethyleneimine (mass fraction is 2-6%) to react for 18-36h, taking out the oxidized porous wood after the reaction, fully rinsing the oxidized porous wood with water, taking out the oxidized porous wood, adding the oxidized porous wood into a glutaraldehyde solution (mass fraction is 0.1-4%) to react for 1-6h at room temperature, fully rinsing the oxidized porous wood with water after the reaction is finished, and (freezing) and drying the oxidized porous wood to obtain the polymer-modified porous wood.

(4) Adding the polymer modified porous wood obtained in the step (3) into catalytic metal ion solution (preferably with the concentration of 2-10mmol/L, preferably silver nitrate solution or ammonium tetrachloropalladate solution), keeping away from light for 0.5-2h, washing with water, adding into metal plating solution (pH is 8-12, metals such as nickel, silver, gold and the like), performing electroless metal deposition for 15-60min, fully rinsing with water after the reaction is finished, and drying (freezing) to obtain the metalized wood.

Compared with the existing metal material, the invention has the following advantages and beneficial effects:

(1) the biomass carbon neutral resource wood is applied to the fields of catalysis, antibiosis and conductive materials, and has positive reference significance for widening the application of low-value wood and improving the added value of the low-value wood. The wood contains a large amount of cellulose, and the cellulose contains abundant hydroxyl groups, and the groups can provide sufficient active sites for chemical modification of wood fibers. In addition, the wood has better porous structure and excellent compressibility after delignification treatment, which provides convenient conditions for the subsequent chemical modification, metallization deposition and the application of catalysis, antibiosis and electric conduction of the porous wood.

(2) The invention obtains the porous wood rich in cellulose through delignification treatment, then cross-links with branched polymer containing amidocyanogen under the action of cross-linking agent to obtain the wood with polymer brush on the surface, then deposits catalytic metal ions on the wood surface through ion exchange, finally carries out metal electroless deposition through the action of the metal ions to obtain the metalized wood, has rich raw material sources, low price, simple preparation process, no toxicity and harm and little environmental pollution, and in the prepared metalized wood, the surface of a metal layer is not covered by the surfactant, the catalytic activity, the antibacterial activity and the conductivity of the prepared metalized wood are not lost basically, and the metal layer is uniformly and stably deposited on the surface of the wood, is not easy to fall off, is convenient to use and can be recycled for a long time, thereby solving the problem that the activity of the metal material is not good because the surfactant is coated on the surface when the metal material is utilized in the prior art, and the difficult problem that the metal material can not be effectively recycled.

Drawings

FIG. 1 is a drawing of metallized wood of different shapes prepared in example 1 of the present invention;

FIG. 2 is an SEM image of a metallized wood prepared according to example 1 of the present invention, with a scale of 20 μm;

FIG. 3 is an enlarged view of the internal structure of the frame in the SEM image of FIG. 2, with a scale of 500 nm;

FIG. 4 is a cyclic compressive stress-strain curve of the metallized wood obtained in example 1 of the present invention;

FIG. 5 is a UV spectrum of metallized wood obtained in example 1 of the present invention catalyzing the degradation of p-nitrophenol;

FIG. 6 is a graph showing the cyclic catalytic ability of the metallized wood obtained in example 1 of the present invention;

FIG. 7 is a graph showing the normalized resistance change of the metallized wood obtained in example 1 of the present invention during the compression process;

FIG. 8 is a digital image of a metallized wood obtained in example 1 of the present invention as an electronic pressure sensor in an actual circuit;

fig. 9 shows the antibacterial ability of the metallized wood obtained in example 1 of the present invention: the experimental results of the paper disc dispersion assay (wherein a is Ni-PW, b is PEI-PW, and c is PW);

FIG. 10 is a graph showing the antibacterial ability of the metallized wood obtained in example 1 of the present invention: results of the turbidity assay.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It should be noted that "normal temperature" and "room temperature" in the present invention mean 15 ℃ to 30 ℃; unless otherwise specified, the reagents used in the present invention are commercially available.

The omitted operations in the invention are all the conventional operations in the field, such as 'freeze drying', namely drying by adopting the conventional freeze drying method for wood in the field; such as "deionized water at pH 10", is also obtained by adjusting the pH to about 10 using an alkaline reagent, which is conventional in the art, using techniques which are conventional in the art.

Example 1

The preparation method of the multifunctional metallized wood material comprises the following steps:

(1) cutting about 20g of basswood into blocks, soaking the basswood into 500mL of boiling mixed aqueous solution containing 6g of sodium hydroxide and 18g of sodium sulfite, taking out the basswood after 10h of reaction, then soaking the basswood into boiling sodium chlorite solution with the mass fraction of 1% until the wood is whitened, fully rinsing the wood with deionized water after the reaction is finished, and obtaining porous wood rich in cellulose after freeze drying;

(2) weighing about 5g of porous wood, soaking the porous wood in 200mL of deionized water with the pH value of about 10, then adding about 2mmol of sodium hypochlorite, reacting for 2 hours, adding 0.5mol/L hydrochloric acid until the pH value of the solution is neutral, stopping the reaction, then soaking the wood in 0.5mol/L hydrochloric acid, washing the wood with deionized water for several times, and freeze-drying to obtain oxidized porous wood;

(3) weighing about 2g of oxidized porous wood, adding about 20mL of polyethyleneimine-methanol solution with the mass fraction of 4%, reacting for 24 hours, fully rinsing with deionized water, then soaking in about 20mL of glutaraldehyde solution with the mass fraction of 2%, reacting for 6 hours at room temperature, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain polymer modified porous wood;

(4) weighing about 2g of polymer modified porous wood, adding the polymer modified porous wood into about 50mL of silver nitrate solution with the molar concentration of 6mmol/L, reacting for 30min in a dark place, fully rinsing with deionized water, taking out and soaking in nickel metal plating solution for metal electroless deposition, reacting for 30min, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain the multifunctional metalized wood material.

The method of preparing metallized wood in example 1 was used to treat raw wood of different shapes, the physical diagram of which is shown in fig. 1. Scanning electron microscope characterization was performed on the metalized wood prepared in example 1, and the results are shown in fig. 2 and 3. FIGS. 2 and 3 show that the microstructure of the metallized wood prepared in example 1 is firmly supported with a micron-level nickel layer, except for a large number of holes, and the thickness of the metal layer is about 1.8 μm; in addition, the relatively well-aligned micropores also provide excellent compression-recovery capability for the metalized wood, as shown in fig. 4, the mechanical compression performance of the metalized wood is slightly reduced after 1000 times of cyclic compression test, which indicates that the metalized wood has excellent compression-recovery capability.

Example 2

(1) cutting about 10g of basswood into blocks, soaking the basswood into 300mL of boiling mixed aqueous solution containing 10g of sodium hydroxide and 15g of sodium sulfite, taking out the basswood after reacting for 12h, then soaking the basswood into boiling sodium chlorite solution with the boiling mass fraction of 0.5 percent until the wood is whitened, fully rinsing the wood with deionized water after the reaction is finished, and obtaining porous wood rich in cellulose after freeze drying;

(2) weighing about 5g of porous wood, soaking the porous wood in 200mL of deionized water with the pH value of about 10, then adding about 3mmol of sodium hypochlorite, reacting for 3 hours, adding 0.5mol/L hydrochloric acid until the pH value of the solution is neutral, stopping the reaction, then soaking the wood in 0.5mol/L hydrochloric acid solution, washing the wood with deionized water for several times, and freeze-drying to obtain oxidized porous wood;

(3) weighing about 2g of oxidized porous wood, adding about 20mL of polyethyleneimine-methanol solution with the mass fraction of about 4%, fully rinsing with deionized water after reacting for 24h, then adding about 20mL of glutaraldehyde solution with the mass fraction of 2%, reacting for 4h at room temperature, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain polymer-modified porous wood;

(4) weighing about 1g of polymer-modified porous wood, adding about 20mL of ammonium tetrachloropalladate solution with the molar concentration of 5mmol/L, reacting for 30min, fully rinsing with deionized water, taking out and soaking in a nickel metal plating solution for metal electroless deposition, reacting for 30min, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain the multifunctional metallized wood material.

Example 3

(1) cutting about 10g of basswood into blocks, soaking the basswood into 300mL of boiling mixed aqueous solution containing 10g of sodium hydroxide and 15g of sodium sulfite, taking out the basswood after reacting for about 12h, then soaking the basswood into boiling sodium chlorite solution with the mass fraction of about 0.5% until the wood is whitened, fully rinsing the wood with deionized water after the reaction is finished, and obtaining porous wood rich in cellulose after freeze drying;

(2) weighing about 3g of porous wood, soaking the porous wood in 100mL of deionized water with the pH value of about 10, then adding about 0.6mmol of sodium hypochlorite, reacting for 5 hours, adding 0.2mol/L of hydrochloric acid until the pH value of the solution is neutral, stopping the reaction, then soaking the wood in 0.2mol/L of hydrochloric acid solution, washing the wood with deionized water for several times, and freeze-drying to obtain oxidized porous wood;

(3) weighing about 1g of oxidized porous wood, adding about 15mL of polyethyleneimine-methanol solution with the mass fraction of 4%, fully rinsing with deionized water after reacting for 24h, then adding about 15mL of glutaraldehyde solution with the mass fraction of 2%, reacting for 4h at room temperature, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain polymer-modified porous wood;

(4) weighing about 1g of polymer modified porous wood, adding about 20mL of silver nitrate solution with the molar concentration of 6mmol/L, reacting for 30min, fully rinsing with deionized water, taking out and soaking in nickel metal plating solution for metal electroless deposition, reacting for 15min, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain the multifunctional metalized wood material.

Example 4

(1) cutting about 5g of basswood into blocks, soaking the basswood into about 200mL of boiling mixed aqueous solution containing 8g of sodium hydroxide and 10g of sodium sulfite, taking out the basswood after reacting for 12h, then soaking the basswood into boiling sodium chlorite solution with the boiling mass fraction of about 0.7 percent until the wood is whitened, fully rinsing the wood with deionized water after the reaction is finished, and obtaining porous wood containing cellulose after freeze drying;

(2) weighing about 2g of porous wood, soaking the porous wood in 100mL of deionized water with the pH value of about 10, then adding about 1.3mmol of sodium hypochlorite, reacting for 3 hours, adding 0.2mol/L of hydrochloric acid until the pH value of the solution is neutral, stopping the reaction, then soaking the wood in 0.2mol/L of hydrochloric acid solution, washing the wood with deionized water for several times, and freeze-drying to obtain oxidized porous wood;

(3) weighing about 1g of oxidized porous wood, adding about 15mL of polyethyleneimine-methanol solution with the mass fraction of 2%, fully rinsing with deionized water after reacting for about 24 hours, then adding about 15mL of glutaraldehyde solution with the mass fraction of 2%, reacting for 5 hours at room temperature, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain polymer-modified porous wood;

(4) weighing about 1g of polymer modified porous wood, adding about 20mL of silver nitrate solution with the molar concentration of 6mmol/L, reacting for about 30min, fully rinsing with deionized water, taking out and soaking in nickel metal plating solution for metal electroless deposition, reacting for about 30min, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain the multifunctional metalized wood material.

Example 5

(1) cutting about 5g of basswood into blocks, soaking the basswood into about 200mL of boiling mixed aqueous solution containing 8g of sodium hydroxide and 10g of sodium sulfite, taking out the basswood after reacting for 10h, then soaking the basswood into boiling sodium chlorite solution with the boiling mass fraction of about 0.7 percent until the wood is whitened, fully rinsing the wood with deionized water after the reaction is finished, and obtaining porous wood containing cellulose after freeze drying;

(2) weighing about 2g of porous wood, soaking the porous wood in 100mL of deionized water with the pH value of about 10, then adding about 1mmol of sodium hypochlorite, reacting for 3 hours, adding 0.2mol/L hydrochloric acid until the pH value of the solution is neutral, stopping the reaction, then soaking the wood in 0.2mol/L hydrochloric acid solution, washing the wood with deionized water for several times, and freeze-drying to obtain oxidized porous wood;

(3) weighing about 1g of oxidized porous wood, adding about 15mL of polyethyleneimine-methanol solution with the mass fraction of 4%, reacting for about 28h, fully rinsing with deionized water, then adding about 15mL of glutaraldehyde solution with the mass fraction of 4%, reacting for 6h at room temperature, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain polymer-modified porous wood;

(4) weighing about 1g of polymer-modified porous wood, adding about 20mL of silver nitrate solution with the molar concentration of 8mmol/L, reacting for 30min, fully rinsing with deionized water, taking out and soaking in nickel metal plating solution for metal electroless deposition, reacting for 30min, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain the multifunctional metalized wood material.

The metalized woods prepared in examples 2-5 were also characterized by scanning with an electron microscope, which also showed a large number of pores and deposited metal layers, and the metalized woods had a certain ability to catalyze the degradation of p-nitrophenol, and the SEM and catalytic performance diagrams thereof were omitted here for the sake of space saving.

Comparative example 1

The preparation method of the metallized wood of the comparative example comprises the following steps:

(1) cutting about 10g of basswood into blocks, soaking the basswood into about 500mL of boiling mixed aqueous solution containing about 7g of sodium hydroxide and about 20g of sodium sulfite, taking out the basswood after reacting for about 12h, then soaking the basswood into boiling sodium chlorite solution with the mass fraction of about 1% until the wood is whitened, fully rinsing the wood with deionized water after the reaction is finished, and obtaining porous wood containing cellulose after freeze drying;

(2) weighing about 5g of porous wood, soaking the porous wood in 100mL of deionized water with the pH value of about 10, then adding about 1mmol of sodium hypochlorite, reacting for 2 hours, adding 0.5mol/L hydrochloric acid solution to stop the reaction, then soaking the wood in 0.5mol/L hydrochloric acid solution, washing the wood with deionized water for a plurality of times, and freeze-drying to obtain oxidized porous wood;

(3) weighing about 2g of oxidized porous wood, adding about 20mL of silver nitrate solution with the molar concentration of 6mmol/L, reacting for about 30min, fully rinsing with deionized water, taking out and soaking in nickel metal plating solution for metal electroless deposition, reacting for about 30min, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain the metalized wood.

Comparative example 2

(1) weighing about 2g of original basswood, fully cleaning the basswood with ethanol and deionized water, then drying the basswood in an oven at 80 ℃ for 1h, soaking the dried basswood in about 20mL of polyethyleneimine-methanol solution with the mass fraction of about 4%, reacting for about 24h, fully rinsing the basswood with deionized water, then soaking the basswood in about 20mL of glutaraldehyde solution with the mass fraction of about 2%, reacting for about 5h at room temperature, fully rinsing the basswood with deionized water after the reaction is finished, and freeze-drying the basswood to obtain the polymer wood.

(2) Weighing about 2g of polymer wood, adding the polymer wood into about 50mL of silver nitrate solution with the molar concentration of about 10mmol/L, reacting for about 30min, fully rinsing with deionized water, then soaking in nickel metal plating solution for metal electroless deposition, reacting for about 30min, fully rinsing with deionized water after the reaction is finished, and freeze-drying to obtain the metalized wood.

The metallized wood prepared in examples 1 to 5 and comparative examples 1 to 2 was subjected to an experimental study of catalytic degradation of p-nitrophenol, the thickness of the nickel metal layer (measured by SEM chart) and catalytic degradation of p-nitrophenol (a mixed solution containing 3mL of 0.1mmol/L of p-nitrophenol and 0.3mL of 0.5mol/L of sodium borohydride was prepared, and 15mg of metallized wood was put therein to conduct a study of catalytic performance of the metallized wood) and the results are shown in Table 1.

TABLE 1 ability of metallized wood prepared in the examples of the invention and comparative examples to catalyze degradation of p-nitrophenol

。

Comparative example 1 is a metallized wood not modified with polyethyleneimine due to the absence of the complexing catalytic factor metal Ag in the porous wood⁺Active groups of (2), Ag being carried out by pore filling only⁺But will release Ag on the surface of the wood during the deionized water rinsing process⁺Removing to make the surface of the porous wood free of Ag⁺The supported metal nickel ions can not be catalyzed to reduce, so that the finally prepared composite wood has almost no deposition of the metal nickel, namely, the composite wood has almost no capability of catalyzing the degradation of the p-nitrophenol.

Comparative example 2 is a polymer wood obtained by cross-linking raw wood without delignification with functional polymer polyethyleneimine via glutaraldehyde, followed by ion exchange, electroless metal deposition, and finally preparation of a metalized wood. Since cellulose is entangled with hemicellulose and lignin in wood, the polymer is only lightly crosslinked on the surface of wood, resulting in its crosslinking to Ag⁺Has lower adsorption capacity, can deposit only a small amount of metallic nickel, and thus has lower capability of catalyzing the degradation of the p-nitrophenol.

The metalized wood in example 1 has high crosslinking rate of polyethyleneimine due to the fact that most of hemicellulose and lignin are removed, and porous wood can be crosslinked with polyethyleneimine through covalent bonds, and the crosslinked rate of the polyethyleneimine is high for catalytic factor Ag⁺The adsorption capacity of the nickel-based metal ion plating solution is relatively strong, and the electroless deposition reaction of nickel metal can be further efficiently completed to obtain ideal target metalized wood;

the metallized wood prepared in example 2 has similar metal layer thickness and catalytic degradation performance as example 1, but the reagent price is much higher than the silver nitrate price because the ammonium tetrachloropalladate is used in the fourth step. Therefore, from an economic point of view, the use of silver nitrate as a metal catalyst is superior to the use of ammonium tetrachloropalladate; for examples 3 and 4, although the prepared metalized wood has stronger capability of catalyzing p-nitrophenol degradation and a thicker nickel metal layer, the performance of each aspect of the prepared metalized wood is far inferior to that of example 1, because the metal nickel ions are not fully reduced due to shorter metal electroless deposition time or lower polyethyleneimine concentration, the content of deposited metal nickel is insufficient, and the capability of catalyzing the p-nitrophenol degradation is further weakened; for example 5, because the glutaraldehyde concentration is high, the crosslinking reaction with the 4% polyethyleneimine solution is rapid and violent, so that the polyethyleneimine is mostly connected on the surface of the wood, which seriously affects the efficiency of adsorbing metal catalyst ions and depositing a metal layer, so that the metal deposited inside and outside the wood is uneven, and the integral capability of catalyzing the degradation of the p-nitrophenol is also affected.

The application of the metallized wood prepared in example 1 of the present invention in the fields of catalysis, conductivity and antibiosis is illustrated by a series of experiments.

Catalytic degradation performance

Respectively preparing 0.1mmol/L p-nitrophenol solution and 0.5mol/L sodium borohydride solution, putting 15mg of the metallized wood (Ni-PW) prepared in the example 1 into a mixed solution consisting of 3mL of the p-nitrophenol solution and 0.3mL of the sodium borohydride solution, and researching the catalytic degradation of the p-nitrophenol, wherein an ultraviolet-visible spectrophotometer is utilized to monitor the change condition of an ultraviolet absorption spectrum of the catalytic system solution in real time, as shown in figure 5; in order to explore the cyclic catalytic capability of the metallized wood, 100mg of the metallized wood (Ni-PW) prepared in example 1 is put into a mixed solution consisting of 5mL of p-nitrophenol solution and 0.5mL of sodium borohydride solution, catalytic degradation is carried out at room temperature, when the color of the solution is changed from yellow to colorless, the Ni-PW is taken out and directly put into fresh p-nitrophenol and sodium borohydride solution, so that the cyclic catalytic degradation study of the metallized wood is carried out, and the cyclic catalytic degradation capability of the Ni-PW is shown in FIG. 6 after 2000 times of cyclic catalysis.

As can be seen from FIG. 5, the ultraviolet absorption characteristic peak of p-nitrophenol is at 400nm, with the addition of Ni-PW, p-nitrophenol is gradually reduced to p-aminophenol (characteristic peak: 300 nm), and can be completely converted into p-aminophenol within 2min, and the corresponding rate constant is 2.31 × 10^-2 s^-1(see table 1) which shows that the metallized wood prepared in example 1 of the present invention has excellent ability to catalyze the degradation of p-nitrophenol.

As can be seen from fig. 6, the metalized wood prepared in example 1 of the present invention has a catalytic ability of p-nitrophenol degradation of more than 90% after 2000 cycles of catalysis, which indicates that the metalized wood prepared in example 1 of the present invention has an excellent cyclic catalytic degradation ability.

The catalytic material provided by patent CN201410336908.X has a rate constant of 0.75 × 10 for catalyzing the degradation of p-nitrophenol^-3 s^-1And it was subjected to only 3 catalytic degradation cycles; the catalyst prepared by the patent CN201811608834.5 has a rate constant of 1.1 x 10 for catalyzing the degradation of p-nitrophenol^-3 s^-1And after 10 times of cyclic catalytic degradation, the catalytic efficiency is still 100 percent; as can be seen from FIGS. 5 and 6, the metallized wood (Ni-PW) prepared in example 1 of the present invention has a reaction rate constant of 2.31X 10 in the research of catalyzing the degradation of p-nitrophenol^-2 s^-1After 2000 cycles, the efficiency is still as high as more than 90%, so that the metallized wood prepared by the method in the embodiment 1 of the invention is far more than most of the existing catalytic materials no matter the catalytic rate or the cyclic catalytic capacity.

Second, conductivity

The metalized wood prepared in example 1 is used as an electronic pressure sensor to be applied to the field of electric conduction by utilizing the excellent compression resilience of the metalized wood and the excellent electric conductivity specific to metal, a multimeter is used for measuring the resistance change of the metalized wood in the compression resilience process, and the normalized resistance of the metalized wood, wherein the compression strain is increased from 0% to 60%, is shown in fig. 7. Normalized resistance = real time resistance/initial resistance. As can be seen from fig. 7, when the initial resistance is 7.9 Ω, the normalized resistance is 1, and as the metallized wood is compressed, the distance between the holes inside it is shortened, the metallized wood becomes tighter, and the conductive substances are better in contact with each other, resulting in a decrease in resistance, and when the compressive strain is 60%, the resistance is reduced to 1.1 Ω, and at this time, the normalized resistance of the metallized wood is 0.139; the metalized wood gradually returned to the original state with the gradual release of the pressure, but the normalized resistance of the metalized wood increased during the rebound process compared to the compression process, because the rebound process exhibited a certain hysteresis behavior, as can be seen from the cyclic compression data (fig. 4). The above data show that the metalized wood prepared in example 1 has sensitive pressure-induced resistance change behavior, and can be used as a pressure sensor in the field of electric conduction.

In order to further explore the conductive ability of the metalized wood and widen the application of the conductive field, the metalized wood prepared in example 1 is applied to a normal circuit as an electronic conductor, and the metalized wood is connected with an LED electronic screen at a voltage of 3V, as shown in FIG. 8. When the metalized wood is not in contact with the conducting wire, the LED electronic screen has no change; however, when the metalized wood is in contact with the wire, the LED screen shows "sc au". This shows that the metalized wood prepared in example 1 has excellent electron conductivity and can be used as a conductor in some special conductive fields.

Third, antibacterial property

The metalized wood prepared in example 1 of the present invention was tested for antibacterial properties using gram-negative bacteria, Escherichia coli (E. coli)E. coli) And gram-positive bacteria staphylococcus aureus (S. aureus) For bacterial model, these two bacteria were inoculated in LB liquid medium and activated at 37 ℃ for 24 hours for use. Evaluating bacteriostatic properties of metalized wood by paper disc diffusion assay, directly contacting cleaned and sized metalized wood with bacterial suspension spread on LB agar plate to obtain delignified wood (PW) and polymer wood (PEI-PW)In the control group, the change of the size of the zone of inhibition corresponding to the three groups of samples was measured when the bacteria were cultured at 37 ℃, and the results are shown in fig. 9. As can be seen from FIG. 9, the bacteria were cultured for 1 day, and the experimental groups were groupedE. coliAndS. aureusthe metalized wood has better bacteriostatic ability, and the bacteriostatic activity of the metalized wood comes from the deposited metal layer; in addition, after the bacteria are cultured for 7 days, the inhibition zone of the experimental group is not reduced at all, which indicates that the metalized wood also has better long-acting antibacterial activity.

The experimental results above were qualitatively evaluated for the bacteriostatic ability of the metalized wood, followed by quantitative further evaluation for the bacteriostatic ability of the metalized wood. The method comprises the following steps of (1) utilizing a turbidity analysis method to research, firstly, extruding 50 mu L of bacterial suspension into a 5mL LB liquid culture test tube, and respectively adding metalized wood, delignified wood (PW), polymer wood (PEI-PW) and deionized water with the same mass, wherein the metalized wood, the delignified wood (PW), the polymer wood (PEI-PW) and the deionized water are used as a control group; then placing the mixed system in a shaking table, and culturing at 180rpm and 37 ℃ for 18 h; finally, the survival of the bacteria was determined, survival = OD of the sample group after 18h of culture₆₀₀OD of blank control group after 18h incubation₆₀₀The specific results are shown in FIG. 10. As can be seen from the figure, after 18h of culture, the survival rate of two bacteria in the experimental group is only about 10%, and the survival rate of the bacteria in the rest three groups of control groups is basically 100%, which indicates that the control group has no bacteriostatic ability, and the metalized wood can inhibit about 90% of bacteria ((R))E. coliAndS. aureus) And (5) growing.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. Use of a multifunctional metallized wood-based material in a catalytic, electrically conductive or antibacterial material, wherein the multifunctional metallized wood-based material is produced by a method comprising the steps of:

(1) cutting wood into blocks, soaking the wood in a boiling mixed aqueous solution of sodium hydroxide and sodium sulfite for reaction, taking out the wood after the reaction is finished, soaking the wood in a boiling sodium chlorite solution for reaction, taking out the wood after the wood is whitened, fully rinsing the wood with water, and drying the wood to obtain porous wood;

the concentration of sodium hydroxide in the mixed aqueous solution in the step (1) is 10-40 g/L, the concentration of sodium sulfite is 30-50 g/L, and the reaction time in the mixed aqueous solution is 4-12 h;

(2) soaking the porous wood obtained in the step (1) in water with the pH value of 8-12, then adding a certain amount of sodium hypochlorite to enable the concentration of the sodium hypochlorite in the solution to reach 5-15mmol/L, reacting for 2-5h, then adding a certain amount of hydrochloric acid until the pH value of the solution is neutral, stopping the reaction, taking out the wood, soaking the wood with the hydrochloric acid, washing the wood with water, and drying to obtain oxidized porous wood;

(3) adding the oxidized porous wood obtained in the step (2) into a methanol solution of polyethyleneimine for reaction, taking out the oxidized porous wood after the reaction, fully rinsing the oxidized porous wood with water, taking out the oxidized porous wood, adding the oxidized porous wood into a glutaraldehyde solution for reaction, fully rinsing the oxidized porous wood with water after the reaction is finished, and drying the oxidized porous wood to obtain polymer-modified porous wood;

(4) adding the polymer-modified porous wood obtained in the step (3) into a catalytic metal ion solution, placing in a dark place, then washing with water, then adding into a metal plating solution, carrying out metal electroless deposition, fully rinsing with water after the reaction is finished, and drying to obtain a multifunctional metallized wood material;

the metal ion solution with catalytic performance in the step (4) is silver nitrate solution or ammonium tetrachloropalladate solution, the concentration is 2-10mmol/L, and the keeping away from light is carried out for 0.5-2 h;

the metal plating solution in the step (4) is nickel, silver or gold metal plating solution, the pH value is 8-12, and the electroless deposition time of metal is 15-60 min;

the mass fraction of the methanol solution of the polyethyleneimine obtained in the step (3) is 2-6%, and the reaction time in the methanol solution of the polyethyleneimine is 18-36 h;

the mass fraction of the glutaraldehyde in the glutaraldehyde solution in the step (3) is 0.1-4%, and the reaction is carried out for 1-6h at room temperature.

2. Use according to claim 1, characterized in that: the wood used in the step (1) is one of basswood, balsa wood, pine wood and birch.

3. Use according to claim 1, characterized in that: the mass fraction of the sodium chlorite solution in the step (1) is 0.5-1%.

4. Use according to claim 1, characterized in that: the concentration of the hydrochloric acid in the step (2) is 0.1-0.5 mol/L.